package org.emergent.android.weave.client;

import org.apache.http.Header;
import org.apache.http.HttpEntity;
import org.apache.http.HttpException;
import org.apache.http.HttpHost;
import org.apache.http.HttpMessage;
import org.apache.http.HttpRequest;
import org.apache.http.HttpRequestInterceptor;
import org.apache.http.HttpResponse;
import org.apache.http.HttpVersion;
import org.apache.http.StatusLine;
import org.apache.http.auth.AuthScope;
import org.apache.http.auth.AuthState;
import org.apache.http.auth.Credentials;
import org.apache.http.auth.UsernamePasswordCredentials;
import org.apache.http.client.CredentialsProvider;
import org.apache.http.client.HttpClient;
import org.apache.http.client.HttpResponseException;
import org.apache.http.client.ResponseHandler;
import org.apache.http.client.methods.HttpDelete;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.client.methods.HttpPut;
import org.apache.http.client.methods.HttpRequestBase;
import org.apache.http.client.protocol.ClientContext;
import org.apache.http.conn.ClientConnectionManager;
import org.apache.http.conn.params.ConnManagerPNames;
import org.apache.http.conn.params.ConnPerRouteBean;
import org.apache.http.conn.scheme.PlainSocketFactory;
import org.apache.http.conn.scheme.Scheme;
import org.apache.http.conn.scheme.SchemeRegistry;
import org.apache.http.conn.scheme.SocketFactory;
import org.apache.http.conn.ssl.AbstractVerifier;
import org.apache.http.conn.ssl.SSLSocketFactory;
import org.apache.http.conn.util.InetAddressUtils;
import org.apache.http.impl.auth.BasicScheme;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.impl.conn.SingleClientConnManager;
import org.apache.http.impl.conn.tsccm.ThreadSafeClientConnManager;
import org.apache.http.params.BasicHttpParams;
import org.apache.http.params.HttpParams;
import org.apache.http.params.HttpProtocolParams;
import org.apache.http.protocol.ExecutionContext;
import org.apache.http.protocol.HttpContext;

import javax.net.ssl.SSLException;
import java.io.IOException;
import java.net.InetAddress;
import java.net.URI;
import java.net.UnknownHostException;
import java.util.Arrays;
import java.util.Collection;
import java.util.Date;
import java.util.HashSet;

/**
 * @author Patrick Woodworth
 */
class WeaveTransport {

    private static final int                    HTTP_PORT_DEFAULT  = 80;
    private static final int                    HTTPS_PORT_DEFAULT = 443;

    private static final HttpRequestInterceptor sm_preemptiveAuth  = new MyInterceptor();
    private static final MyResponseHandler      sm_responseHandler = new MyResponseHandler();

    private static final HttpParams             sm_httpParams;

    static {
        HttpParams params = new BasicHttpParams();
        HttpProtocolParams.setVersion(params, HttpVersion.HTTP_1_1);
        HttpProtocolParams.setContentCharset(params, "UTF-8");
        HttpProtocolParams.setUserAgent(params, WeaveConstants.USER_AGENT);
        HttpProtocolParams.setUseExpectContinue(params, false);
        // params.setParameter(HttpProtocolParams.USE_EXPECT_CONTINUE, false);
        params.setParameter(ConnManagerPNames.MAX_TOTAL_CONNECTIONS, 30);
        params.setParameter(ConnManagerPNames.MAX_CONNECTIONS_PER_ROUTE, new ConnPerRouteBean(30));
        sm_httpParams = params;
    }

    private final SocketFactory                 m_sslSocketFactory;

    private final ClientConnectionManager       m_clientConMgr;

    public WeaveTransport(){
        this(WeaveConstants.CONNECTION_POOL_ENABLED_DEFAULT);
    }

    public WeaveTransport(boolean useConnectionPool){
        this(useConnectionPool, WeaveConstants.ALLOW_INVALID_CERTS_DEFAULT);
    }

    public WeaveTransport(boolean useConnectionPool, boolean allowInvalidCerts){
        m_sslSocketFactory = createSocketFactory(allowInvalidCerts);
        m_clientConMgr = useConnectionPool ? createClientConnectionManager(true) : null;
    }

    public void shutdown() {
        // if (m_clientConMgr != null)
        // m_clientConMgr.shutdown();
    }

    public WeaveResponse execDeleteMethod(String username, String password, URI uri) throws IOException, WeaveException {
        HttpDelete method = new HttpDelete(uri);
        return execGenericMethod(username, password, uri, method);
    }

    public WeaveResponse execGetMethod(String username, String password, URI uri) throws IOException, WeaveException {
        HttpGet method = new HttpGet(uri);
        return execGenericMethod(username, password, uri, method);
    }

    public WeaveResponse execPostMethod(String username, String password, URI uri, HttpEntity entity)
                                                                                                     throws IOException,
                                                                                                     WeaveException {
        HttpPost method = new HttpPost(uri);
        method.setEntity(entity);
        return execGenericMethod(username, password, uri, method);
    }

    public WeaveResponse execPutMethod(String username, String password, URI uri, HttpEntity entity)
                                                                                                    throws IOException,
                                                                                                    WeaveException {
        HttpPut method = new HttpPut(uri);
        method.setEntity(entity);
        return execGenericMethod(username, password, uri, method);
    }

    private void setMethodHeaders(HttpMessage method) {
        method.addHeader("Pragma", "no-cache");
        method.addHeader("Cache-Control", "no-cache");
    }

    private WeaveResponse execGenericMethod(String username, String password, URI uri, HttpRequestBase method)
                                                                                                              throws IOException,
                                                                                                              WeaveException {
        HttpClient client = null;
        try {
            client = createHttpClient(username, password);
            return execGenericMethod(client, uri, method);
            // } catch (IOException e) {
            // throw new WeaveException("Unable to communicate with Weave server.", e);
        } finally {
            if (m_clientConMgr == null && client != null) {
                client.getConnectionManager().shutdown();
            }
        }
    }

    private WeaveResponse execGenericMethod(HttpClient client, URI uri, HttpRequestBase method) throws IOException,
                                                                                               WeaveException {
        setMethodHeaders(method);
        MyResponseHandler responseHandler = sm_responseHandler;
        String scheme = uri.getScheme();
        String hostname = uri.getHost();
        int port = uri.getPort();
        HttpHost httpHost = new HttpHost(hostname, port, scheme);
        WeaveResponseHeaders responseHeaders = null;
        try {
            WeaveResponse response = client.execute(httpHost, method, responseHandler);
            response.setUri(uri);
            responseHeaders = response.getResponseHeaders();
            return response;
        } catch (WeaveResponseException e) {
            responseHeaders = e.getResponseHeaders();
            throw e;
        } finally {
            if (responseHeaders != null) {
                // long backoff = responseHeaders.getBackoffSeconds();
                // if (backoff > 0) {
                // long newbackoff = System.currentTimeMillis() + backoff;
                // m_backoff.set(newbackoff);
                // }
            }
        }
    }

    private DefaultHttpClient createDefaultHttpClient() {
        ClientConnectionManager connectionManager;
        if (m_clientConMgr != null) {
            connectionManager = m_clientConMgr;
        } else {
            connectionManager = createClientConnectionManager(false);
        }
        return new DefaultHttpClient(connectionManager, sm_httpParams);
    }

    private HttpClient createHttpClient(String userId, String password) {
        DefaultHttpClient retval = createDefaultHttpClient();
        Credentials defaultcreds = new UsernamePasswordCredentials(userId, password);
        retval.getCredentialsProvider().setCredentials(AuthScope.ANY, defaultcreds);
        retval.addRequestInterceptor(sm_preemptiveAuth, 0);
        return retval;
    }

    private ClientConnectionManager createClientConnectionManager(boolean threadSafe) {
        SchemeRegistry schemeRegistry = new SchemeRegistry();
        schemeRegistry.register(new Scheme("http", PlainSocketFactory.getSocketFactory(), HTTP_PORT_DEFAULT));
        schemeRegistry.register(new Scheme("https", m_sslSocketFactory, HTTPS_PORT_DEFAULT));
        if (threadSafe) {
            return new ThreadSafeClientConnManager(sm_httpParams, schemeRegistry);
        } else {
            return new SingleClientConnManager(sm_httpParams, schemeRegistry);
        }
    }

    private static SocketFactory createSocketFactory(boolean allowInvalidCerts) {
        SocketFactory sslSocketFactory;
        if (allowInvalidCerts) {
            sslSocketFactory = new WeaveSSLSocketFactory();
        } else {
            sslSocketFactory = SSLSocketFactory.getSocketFactory();
            ((SSLSocketFactory) sslSocketFactory).setHostnameVerifier(new WeaveHostnameVerifier());
        }
        return sslSocketFactory;
    }

    public static class WeaveResponseHeaders {

        private final Header[] m_headers;

        public WeaveResponseHeaders(HttpResponse response){
            m_headers = response.getAllHeaders();
        }

        public Header[] getHeaders() {
            return m_headers;
        }

        public Date getServerTimestamp() {
            Date retval = null;
            String ststamp = getHeaderValue(WeaveHeader.X_WEAVE_TIMESTAMP);
            if (ststamp != null) retval = WeaveUtil.toModifiedTimeDate(ststamp);
            return retval;
        }

        public long getBackoffSeconds() {
            long retval = 0;
            try {
                String valStr = getHeaderValue(WeaveHeader.X_WEAVE_BACKOFF);
                if (valStr != null) retval = Long.parseLong(valStr);
            } catch (Exception ignored) {
            }
            return retval;
        }

        private String getHeaderValue(WeaveHeader header) {
            return getHeaderValue(header.getName());
        }

        private String getHeaderValue(String headerName) {
            for (Header header : m_headers) {
                if (headerName.equals(header.getName())) return header.getValue();
            }
            return null;
        }
    }

    @SuppressWarnings("serial")
    public static class WeaveResponseException extends HttpResponseException {

        private final WeaveResponseHeaders m_responseHeaders;

        public WeaveResponseException(int statusCode, String reasonPhrase, HttpResponse response){
            // super(statusCode, String.format("statusCode = %s ; reason = %s", statusCode, reasonPhrase));
            super(statusCode, reasonPhrase);
            m_responseHeaders = new WeaveResponseHeaders(response);
        }

        public WeaveResponseHeaders getResponseHeaders() {
            return m_responseHeaders;
        }

        @Override
        public String toString() {
            String s = getClass().getName();
            s += ": (statusCode=" + getStatusCode() + ")";
            String message = getLocalizedMessage();
            return (message != null) ? (s + " : " + message) : s;
        }
    }

    /**
     * Based on BasicResponseHandler
     */
    private static class MyResponseHandler implements ResponseHandler<WeaveResponse> {

        /**
         * Returns the response body as a String if the response was successful (a 2xx status code). If no response body
         * exists, this returns null. If the response was unsuccessful (>= 300 status code), throws an
         * {@link org.apache.http.client.HttpResponseException}.
         */
        public WeaveResponse handleResponse(final HttpResponse response) throws HttpResponseException, IOException {
            StatusLine statusLine = response.getStatusLine();
            if (statusLine.getStatusCode() >= 300) {
                throw new WeaveResponseException(statusLine.getStatusCode(), statusLine.getReasonPhrase(), response);
            }
            return new WeaveResponse(response);
        }
    }

    private static class MyInterceptor implements HttpRequestInterceptor {

        public void process(final HttpRequest request, final HttpContext context) throws HttpException, IOException {
            AuthState authState = (AuthState) context.getAttribute(ClientContext.TARGET_AUTH_STATE);
            CredentialsProvider credsProvider = (CredentialsProvider) context.getAttribute(ClientContext.CREDS_PROVIDER);
            HttpHost targetHost = (HttpHost) context.getAttribute(ExecutionContext.HTTP_TARGET_HOST);
            if (authState.getAuthScheme() == null) {
                AuthScope authScope = new AuthScope(targetHost.getHostName(), targetHost.getPort());
                Credentials creds = credsProvider.getCredentials(authScope);
                if (creds != null) {
                    authState.setAuthScheme(new BasicScheme());
                    authState.setCredentials(creds);
                }
            }
        }
    }

    /**
     * @author Patrick Woodworth
     */
    static class WeaveHostnameVerifier extends AbstractVerifier {

        public void verify(String host, String[] cns, String[] subjectAlts) throws SSLException {
            if (isIPAddress(host) && cns != null && cns.length > 0 && cns[0] != null) {
                HashSet<String> expandedAlts = new HashSet<String>();
                resolveHostAddresses(cns[0], expandedAlts);
                if (subjectAlts != null) expandedAlts.addAll(Arrays.asList(subjectAlts));
                subjectAlts = expandedAlts.toArray(new String[expandedAlts.size()]);
            }
            verify(host, cns, subjectAlts, false);
        }

        private static void resolveHostAddresses(String cn, Collection<String> retval) {
            try {
                InetAddress[] addresses = InetAddress.getAllByName(cn);
                for (InetAddress address : addresses) {
                    retval.add(address.getHostAddress());
                }
            } catch (UnknownHostException e) {
                Dbg.d(e);
            }
        }

        private static boolean isIPAddress(final String hostname) {
            return hostname != null
                   && (InetAddressUtils.isIPv4Address(hostname) || InetAddressUtils.isIPv6Address(hostname));
        }
    }
}
